Resources are needed by investigators who are developing new compounds so that the potential adverse toxicological activity of the compounds can be evaluated before they can be taken into clinical trials. This is a very expensive process and is beyond the resources of almost all investigators. PET, SPECT, and MRI imaging in humans by providing toxicology and safety assessment of promising, target-selective compounds. The program also provides limited assessment of novel psychoactive agents for clinical research and as potential therapeutics. Toxicology and safety data generated by the program will be used to support an Investigational New Drug (IND) application to the Food and Drug Administration (FDA), or for Radioactive Drug Research Committee (RDRC) evaluation of a compound for human studies. The contract will evaluate toxicity and safety of compounds submitted for testing. This may include (but is not limited to) novel chemical entities, structural analogs of compounds with an IND, or analogs of FDA-approved drugs.